Method for the preparation of fuel oil



April 27, 1937. R. l.. SAVAGE, JR

METHOD FOR THE yPREPARATION OF FUEL OIL Filed June 13,` 1934 M Y Wm w mmf/w tion Serial No. 633,228, Carl E. Lauer et al., led

` or fuel oil base.

Patented Apr. Z7, 1937 galassi' Mn'rnon Fon THE raiErARA'rroN oF FUEL @PFIQE Ruins L; Savage, Jr., Port Arthur, Tex., assigner to 'Elie Texas Company, New York, N. Y., a corporation of Delaware Application June 13, 1934, Serial No. '730,379 i2 claims. (o1. 19e-14s) The present invention relates to a method of preparing heavy fuel oil from acid-oil sludge derived from the treatment of mineral oils With sulfuric acid.

The invention primar-ily contemplates a meth-od of preparing fuel oil from acid-oil sludge, resulting from the sulfuric acid treatment of mineral lubricating and light oils, that is ordinarilycon- Y sidered a by-product of little commercial value, which consists essentially in separating out the oil-soluble portion ofthe sludge and subjectingr it to a purifying treatment, in accordance with` the invention, to produce a relatively heavy fuel oil base of satisfactory merchantable grade.

Normally the acid-oil sludge resulting from the sulfuric acid treatment o-f mineral' oils consists of a portion of tarry or pitch-like substance which is insoluble and immiscible in eitherV oil or water, a portion of oily substance which is soluble in a mineral oil diluent, and aportion of dilute sulfuric acid, and includes a relatively small amount of sulfonic acids and complex sulfur compounds.

'I'he present invention is a specic improvement on the process disclosed in co-pending applica- According to the present improvement, a portion of the light oil diluent uncontaminated With sludge is passed through the heater and introduced into the chamber to heat the acid sludge therein.` By operating in this manner higherV 5 temperatures may safely be employed in the oilheating step and the danger of coke deposition in the heating tubes is substantially eliminated. This prolongs the life of the equipment and enables longer runs to be made. The clean light oil is more refractory to decomposition and coke formation than the deacidied sludge, and may be heated to a higher temperature without depOSiting coke in the tubes. For example, thisrlight oil may be heated to a temperature of 800 F. or 15 higher, but, since itis preferably not maintained at such temperaturefor a substantial period of time, little cracking occurs. f

In order to more fullydescribe the invention, reference is now made to the single figure of `the accompanying drawing illustrating in diagrammatic elevation a. preferred form of apparatus for carrying on the invention. i

The numeral I is applied to a chute through source not shown, into a disintegrating or sepa!- ration tank 2, which has a Water co-nnection 3, a steam connection A, and a diluent oil connection 5. When a suiiicent amount of the sludge has been delivered into the tank 2, diluent oil and Waterv may be delivered into the tank for the purpose of thinning the sludge, by diluting the oilsoluble portion and the acid portion present, to` such an extent that a. separation of the acid, oily portion and tarry portion may also be effected. Following the addition of the diluent oil and Water, steam is sprayed into the lower portion of "the tank and a vigorous agitation and Warming of the mass or" sludge and diluent is carried on until September 15, 1932. In the process disclosed in that application an acid-oil sludge is agitated With steam in the presence of Water and alight diluent oil, such as gas oil. In the case of sludges from the treatment of petroleum light oils, it vvill be obvious to those skilled in the art that the above described separation may be simplified. As Well known in the art, the oil-soluble portion of the petroleum light oil sludges may be separated from the main part of the unconsumed acid by Washing with Water and without the use of any diluent oil. The acidic oil thus derived may then be treated in accordance with the invention. Y After settling, the

oil-soluble portion of the sludge, containing diluent light oil, is mildly heated to thereby decomposev and volatilize the contained .acidic compounds which are removed, and the deacidied oil is then subjected to Ydistillation vto remove the light oil and produce a residue of merchantable fuel oil The heating to decompose acidic compounds is effected preferably by introducing the mixture Yof diluent and acid sludge into the upper part of `a chamber where it comes into contact with an oil heated to a high temperature of `about '750 F. or over. The deaoidied sludge containing diluent light oil' is then preferably passedA throughfatubular heater and heated to about/750 F., and a part of this heated oil is introduced into the chamber to serve as the hot oil for contacting Avvitli the acid sludge.y

fected and the separable portions are then separated out by'settling. In this step, three layers Will ordinarily be formed, which consist of Weak acid, the tarry oil-insoluble portion, and the dilute oily portion and tarry portion may then be drawn off into a. second tank 8, through a line t, and the remaining Weak acid may be drawn off to a recovery system through a line 1.

Water connection IE), and a steam connection ll. In this tank a repetition of the disintegrating and settling of the sludge, described as being carried on in tank 2, is eiected and the resulting which acid-oilsludge may be delivered, from a a fairly thorough disintegration of the mass is ef- 40 oil-soluble portion. The upper layers of dilute ,4:5`

The tank 8 has' a diluent oil connection 9, a 50.

oil-soluble portion and tarry portion. may be fl drawn olf into settling tanks i4 or l5 while the dilute acid may be withdrawn to a recovery system through a lme I3.

The oil-soluble and the oil-insoluble portions of the sludge are preferably delivered alternately into settling tanks I4 and l5, in which a separation of the two portions is effected. By ernploying two settlers, it is possible to carry on separation in one of the settlers while the other is being drained and refilled, thus making avail-V able a continuous supply of sludge for the process. The oil-soluble portion is preferably' Withdrawn from one of the settlers at a time through a line I6 by a pump I1, while the tarry portion may be drained off through a line f8 or a lineYl9`.

The oil-soluble portion withdrawn by a pump H may contain slight amounts of sulfuric acid, sulfonic acids, and other acidic sulfur compounds. This portion is preferably delivered through a line 20 to the upper portion of a vessel 2l which contains a series of baifles. 22. As it moves downwardly through the vessel over the baies 22, it is brought into contact with a heat-carrying medium, to be hereinafter described, by which it is. rapidly heated to a temperature at which the water content vaporizes and the acidic sulfur compounds are decomposed and' vaporized. This vaporization and decomposition readily takes place under the temperatures existing in the vessel which may vary somewhat over a range of about 380 to 420 F. at about atmospheri` pressure. y

In the novel manner of this invention, the heating of the acid-oil sludge to a point of decomposition and volatilization of the acidic sulfur compounds is effected with ease and economy, with the' result that the life of the equipment is greatly prolonged. and the corrosive effect of the decomposition products is substantially avoided.

The heat-carrying medium, consisting of a portion of a clean distillate of the nature of clean gas oil, is injected into the vessel 2l,at a point preferably somewhat lower than the entrance of the untreated oil portion, and preferably at a temperature of about 800 F. The heat imparted by the hot oil effects the desired decomposition of the corrosive sulfur compounds, converting them into vaporous form, That portionof the oil which might have been vaporized in the heating step is cooled and condensed by its contact with the cooler sludge, and falls to the bottom of the vessel 2| together with the oil content of the sludge which has now been substantially freed from corrosive compounds.

'I'he vapors evolved from the vessel 2| by the heat interchange between the cool acid-oil sludge and the4 hot gas oil are delivered overhead through a linel23, while the unvaporized oil portion, which has been freed of water and acidic sulfur compounds, together with the gas oil, is accumulated in the lower portion of the tower 2l. The pressure in the Vessel 2| is preferably maintained at about 15 to 20 pounds per square inch gauge, but pressures below or above this may be used if desired.

The vapors of decomposed acidic sulfur com-- pounds, occasionally containing a small proportion of light oil such as naphtha vapor, are

ejected from the vessel 2l by a jet' condenser 24 by which they are brought into contact with a neutralizing alkaline material which is supplied from a tank 25 by a pump Z6 through a line 2l,

vtogether with cooling water which may be supplied through a line 28. The water and naphtha from the jet condenser 24 are dropped into a separator 29 which is provided with an oil or vapor outlet line 30 and a water drain line 3l. Preferably milk of lime is employed as the alkaline material and in such quantity that a substantially neutral solution results. However, other alkaline materials, such as caustic soda, soda ash and Waste alkaline solutions, may also be used.

A pump 35 withdraws purified dilute oil-sludge from the lower portion of the vessel 2| through a line 36 and delivers it through a line 3l into a suitable heater 38 where the temperature is raised to about 500 or 600 F., or higher if necessary, to ash off contained lighter diluent oil to a desirable extent to thereby bring the remaining fuel oil or base within specification limits. The thus heated oil is delivered through aline 39 into a vaporizing vessel 45 which contains a series of bailles 46.

It may thus be seen that the heavier portions of the sludge oil, in mixture with the light portions need be heated only enough to ash off the contained light diluent oil.

In the vessel 45, a diluent oil, which as previously mentioned may be of the nature of gas oil, is substantially vaporized from the associated heavier oil resulting from the sludge which remains as a purified residue, and constitutes a homogeneous fuel oil or base which may be blended with other petroleum fractions.

The vapors evolved in the vessel 45 consist mostly of the vapors of the diluent lgas oil, but

may include a small amount of lighter hydrocarbons, which may be of the nature of naphtha, together with small portions of heavier constituents and uncondensable gas produced in the heating step. By applying reflux cooling to the upper portion of the vessel, it isA possible to cleanse the vapors therein of the heavier constituents, so that the vapors may emerge free of this heavy fraction. Any cooling medium may be used as a reflux, although it is preferable to use a gas oil of the nature of that vaporized in the vessel 45.

The vapors are conducted overhead from the vessel 45 through a line 4T to a fractionator 48 in which the gas oil fraction is condensed, and the naphtha, if there be any, and gases are withdrawn overhead through a line 49 to a condenser 50. It may also be desirable to apply reiiux cooling to the upper portion of the fractionator 48 to cleanse the vapors before they are removed from the fractionator, in which case it may be preferable to return a portion of the naphtha condensed in the condenser 59, or a portion of the light gas oil may be used.

The remaining unvaporized material in the vessel 45, which is the purified fuel oil or base material, is Withdrawn through a line 52 through a cooler 53 to storage.

The condensate from the vessel 48, which is the recovered diluent oil, is withdrawn through a line 57, a portion of which may be recycled to the disintegrators 2 and 8 through lines 60 and 62 and another portion may be diverted through line 6l to serve as a heat-carrying inedium as will be more fully described presently. A release line 65 is provided for releasing surplus portions of the diluent oil from the system. Provision is made by means of the pan-tray 55 and the draw-off pipe 5G for removing clean recycle oil or gas oil from a point somewhere above the bottom of vessel 48.

ao'raeea That portion :of the .clean oil' which may be diverted through the line` si is passedY through to a coil heater it and transferred through pipes li andlf into the lower portion of the decomposing and Vvaporising'vessel 2l where, in open contact with 'the acid-.oil sludge entering above, it provides the heat necessary to accomplish `the decomposition and vaporization oftheundesirable acidic compounds present in the sludge oil.

It may be found desirable at times to 4heat somewhat more clean oil in heater lt than is necessary for use in heating the sludge in the vessel 2l, and the surplus maybe diverted through a line 'it to join the cooler purified sludge oil en route from the heater 38 to the flashing vessel 45 to aid in vaporizing the diluent oil content; or, in an alternative mode of operation, the clean oil may be heated to a somewhat higher temperature without increasing its volurne.

In still another mode the heater 38 rmay be `:3y-passed entirely by the purified sludge oil and the purified oil be transferred direct from the base of the vessel 2i through a line lil into the line 39 where it may be further heated by direct contact with a surplus portion of more highly heated clean oil from the heater 10, and the het mixture may be flashed in the vessel t5. Thus the arrangement for heating the untreated acid-oil sludge in the vessel 2l to decompose and vaperize the acidic impurities, and for ultimaten ly raising the temperature of the purified oil sludge to vaporize the contained gas oil, is very flexible.

claim:

1. The process of treating an acid-oil sludge containing objectionable acidic sulfur compounds which comprises delivering the sludge `into a heating chamber, passing a hot refractory diluent oil into the chamber in direct contact with the sludge to heat the same and effect decomposition and vaporization of the acidic sulful compounds, the heating being controlled to avoid any substantial carbonization or cracking of the said sludge, withdrawing the resulting vapors, collecting the purified oil sludge together with the refractory diluent oil, then separating the refractory diluent oil by fractional distillation while removing the purified oil sludge as a residual product of merchantable fuel oil grade, and heating the refractory diluent oil and introducing it into the chamber as the said hot oil to effect heating and decomposition of the acidic sulfur compounds therein.

2. The process of treating an acid-oil sludge containing objectionable acidic sulfur compounds and a refractory diluent oil which comn prises delivering the sludge into a heating cham ber, passing a hot refractory diluent oil into the chamber in direct contact with the sludge to heat the same and effect decomposition and vaporization of the acidic sulfur compounds, the heating beingcon'trolled to avoid any substantial carbonization or cracking of the said sludge,

r withdrawing the resulting vapors, collecting the purified oil sludge together with the refractory diluent oil, then separating the refractory dilun ent oil by fractional distillation while removing the purified oil sludge as a residual product of merchantable fuel oil grade, and heating a portion of the refractory diluent oil and introducing it into the chamber as the said hot oil to effect heating and decomposition of the acidic sulfur compounds therein;

3. The process of treating an acid-oil sludge containing objectionable acidic Isulfurr "compounds and arefactory'diluent oilwhich com,n prises delivering the sludgev into a heating chamber, passing a hot refractory diluent oil into the chamber indirect contact with the sludge to heat the same and effect 'decomposition and vaporization of the acidic sulfur compounds, withdrawing the resulting vapors, collecting the puried oil sludge together with the refractory diluent oil, then further heating the mixture by admixing it with hot refractory diluent oil,and vaporizing the refractory diluent oil therefrom by hashing the mixture into a distillation sone leaving the purified oil sludge as a residual product of merchantable fuel oil grade.

4. The process of treating an acid-oil sludge containing objectionable acidic sulfur compounds and a refractory diluent oil which'comprises delivering the sludge into a heating cham ber, passing a hot refractory diluent oil into-the chamber in direct contact with the sludge to heat the same and effect decomposition and vaporisation of the acidic sulfur compounds, withdrawing the resulting vapors, collecting the puried oil sludge together with the refractory diluent oil, then heating the mixture in a coil to atemperature below that at which coke begins to form in the coil, and further heating the mixture by admixing it with hot refractory diluent oil, and vaporizing the refractory diluent oil therefrom by flashing the mixture into a distillationzone leaving the purified oil sludge as a residual product of merchantable fuel oil grade.

5. `The process of treating an acid-oil sludge containing objectionable acidic sulfur co1n-n pounds and a refractory diluent oil which comprises delivering the sludge into the upper part of a heating chamber, introducing a het oil into the lower portion of the chamber and permitting a portion at least of the hot oil to vaporize therein, effecting contact between the hot vapors and downowing sludge whereby the lat ter is heated and the acidic compounds are decomposed and vaporized and the hot oil vapors are substantially condensed, the heating being controlled to avoid any substantial carbonization or cracking of the said sludge, withdrawing the resulting vapors, collecting the puried oil sludge containing refractory diluent oil, separating the refractory oil therefrom by fractional distillation leaving the puried oil sludge as a residual preduct of merchantable fuel oil grade, collecting the refractory oil, and heating a portion thereof in a coil and introducing it into the chamber as the said hot oil to effect heating and decomposii tion of the acidic compounds therein.

6. The method according to claim 5 in which the refractory diluent oil is heated prior to introduction into the chamber to a temperature of the order of about 800 F.

7. The method according to claim 5 in which the oil sludge is heated in the chamber to a temperature of about S80-420 F.

8. The method according to claim 1 in which the refractory diluent oil is heated prior to intro duction into the chamber to a temperature of the order of about 800 F.

9. The method according to claim 1 in which the oil sludge is heated in the chamber to a tempera-ture of about 380-420" F.

10. The process of treating an acid-oil sludge containing objectionable acidic sulfur compounds which comprises separating out the oilsoluble fraction of the sludge, delivering said fraction into a heating chamber, passing a hot refractory diluent oil into the chamber in direct contact with the said fraction to; heat the same and effect decomposition and vaporization of the acidic sulfur compounds, the heating being controlled to avoid any substantial carbonization or cracking of the said sludge, withdrawing the resulting vapors, collecting the puried fraction together with the refractory oil, then separating the refractory oil by fractional distillation While removing the puried fraction as a residual product of merchantable fuel oil grade, and heating the refractory oil and introducing it into the chamber as the said hot oil to eiTect heating and decomposition of the acidic sulfur compounds therein.

11. The process of treating an acid-oil sludge containing objectionable acidic4 sulfur compounds which comprises separating out the oilsoluble fraction of the sludge, delivering said fraction into a heating chamber, passing a hot refractory diluent oil into the chamber in direct contact with the said fraction to heat the same and effect decomposition and vaporization of the acidic sulfur compounds, withdrawing the resulting vapors, collecting the puried fraction together with the refractory diluent oil, then further heating the mixture by admixing it with hot refractory diluent oil and vaporizing the refractory diluent oil therefrom by flashing the mixture into a distillation zone, leaving the purified fraction as a residual product of merchantable fuel oil grade.

12. The process of treating acid sludge which comprises admixing sludge with Water and a. diluent oil, allowing the sludge to separate into an upper acid-oil layer, a middle sludge layer containing oil insolublev carbonaceous material and a bottom aqueous acid layer, separating the top acid-oil layer, passing the said acid-oil layer into a heating chamber, introducing a hot refractory diluent oil into the chamber in direct contact with the said acid-oil layer to heat the same and effect decomposition and vaporization of acidic sulfur compounds therein, the heating being controlled to avoid any substantial carbonization or cracking of the said sludge, withdrawing the resulting vapors, collecting the puried layer together with the refractory diluent oil, then separating the refractory diluent oil by fractional distillation while removing the purified layer as a residual product of merchantable fuel oil grade, and heating the separated refractory diluent oil and introducing it into the chamber as the said hot oil.

RUFUS L. SAVAGE, JR. 

